The present invention relates to medical devices. More particularly, the present invention relates to embolic protection devices and methods for capturing emboli within a body vessel.
Treatments for a stenotic lesion provide a potential in releasing blood clots and other thrombi plaque in the vasculature of the patient. One example is the treatment for a carotid artery stenosis. Generally, carotid artery stenosis is the narrowing of the carotid arteries, the main arteries in the neck that supply blood to the brain. Carotid artery stenosis (also called carotid artery disease) is a relatively high risk factor for ischemic stroke. The narrowing is usually caused by plaque build-up in the carotid artery. Plaque forms when cholesterol, fat and other substances form in the inner lining of an artery. This formation process is called atherosclerosis.
Depending on the degree of stenosis and the patient's overall condition, carotid artery stenosis has been treated with surgery. The procedure (with its inherent risks) is called carotid endarterectomy, which removes the plaque from the arterial walls. Carotid endarterectomy has proven to benefit patients with arteries substantially narrowed, e.g., by about 70% or more. For people with less narrowed arteries, e.g., less than about 50%, an anti-clotting drug may be prescribed to reduce the risk of ischemic stroke. Examples of these drugs are anti-platelet agents and anticoagulants.
Carotid angioplasty is a more recently developed treatment for carotid artery stenosis. This treatment uses balloons and/or stents to open a narrowed artery. Carotid angioplasty is a procedure that can be performed via a standard percutaneous transfemoral approach with the patient anesthetized using light intravenous sedation. At the stenosis area, an angioplasty balloon is delivered to predilate the stenosis in preparation for stent placement. The balloon is then removed and exchanged via catheter for a stent delivery device. Once in position, a stent is deployed across the stenotic area. If needed, an additional balloon can be placed inside the deployed stent for post-dilation to make sure the struts of the stent are pressed firmly against the inner surface of the vessel wall.
During the stenosis procedure however, there is a risk of such blood clots and thrombi being undesirably released into the blood flow within the vasculature. Embolic protection to capture emboli within the vasculature is a growing concern in the medical industry. Currently, there are a number of approaches for embolic protection to prevent emboli from traveling within the vasculature, causing an undesirable embolism, e.g., pulmonary embolism. For example, vena cava filters are more commonly being used for trapping blood clots and emboli in the vena cava filter to prevent pulmonary embolism. Also, anti-platelet agents and anticoagulants may be used to breakdown blood clots. Moreover, snares and baskets (e.g., stone retrieval baskets) are more commonly used for retrieving urinary calculi. Additionally, occlusion coils are commonly used to occlude aneurysms and accumulate thrombi in a body vessel. Embolic or distal protection devices have been implemented to capture emboli from a stenotic lesion undergoing angioplasty.
During delivery or retrieval of an embolic protection device, it is desired that the cross over profile of the device is maintained as small as possible to minimize contact with the stenotic lesion. Contact with the stenotic lesion increases the risk of blood clots and thrombi being undesirably released into the blood flow within the vasculature. Moreover, during retrieval of the embolic protection device, there is also a risk of the trapped emboli escaping therefrom. This may occur during retrieval of the device and emboli trapped therein.
Thus, there is a need to provide improved devices and methods for distally protecting and capturing emboli within a body lumen during a stenosis procedure.